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31.
32.
The central theme of this paper is the current interest in most educational institutions in moving from teaching to learning as their main system model and the implications which technology media have for unravelling the debate and influencing the resulting practice (for example see Active Learning: Using the Internet for Teaching, Number 2, July, 1995), Our chosen strategy for dealing with the central theme is to consider how we use language, metaphor and models to describe systems for teaching and learning and what is the role of technology in these systems. In particular we describe how the Open University is moving from an analysis of individual technologies to a synthesis of the educational ideas into a sustainable system that conforms to the University's policy of supported open learning. This includes focusing on open and equal access to courses, considerable attention to staff development and training (specifically in core teaching areas such as face to face tuition, correspondence tuition, student support, telephone and other media supported communication) as well as the necessity and value of reflection on practice (e.g. see Baker, Tomlinson et al,, 1996). In this first section, taking as our starting point the traditional linear view of educational structures, we build upon the notion of the learning system and describe this as an approach with a somewhat long and surprising history originating in the Socratic method. An eductive, cyclic learning model is introduced, and the historical impact of technology on this model is briefly reviewed in a global context by addressing the specific issue of access from the developing countries. Following from this, in sections two and three two types of teaching are described, under the labels of conventional and distance. It is argued that each has strengths and tendencies towards the eductive learning system introduced in section one. However, it is also argued that each has flaws which provide problems for the development of a learning system which can be sustained at distance. An analysis based upon metaphor is applied. In section four, it is then argued that in the conventional model there is a system with excellent learning potential but with an organisational structure which often does not encourage it whereas in the distance model there is the potential organisation for providing feedback but often little effective use made of it. That lack of use includes the new technologies which are now being focused on by the Open University, both in terms of the INSTILL initiative (Integrate New Systems and Technologies Into Lifelong Learning) and the Technology Strategy for Academic Advantage (Laurillard, Christmas et al., 1996). These technologies are argued, in section five, to be capable of being tactically effective in stimulating and supporting the strategic aim of learning. Technology mediation is discussed both in terms of course-based teaching and in terms of research opportunities. In section six a range of problem/opportunity areas of immediate concern for the extension of this technologically mediated system to the developing countries are discussed, while policy implications for the extension of supported open learning are drawn out in section seven. These include policies toward co-learning, access to learning, quality standards and the authorship of educational material. 相似文献
33.
Insider action research describes the process when a member of an organisation undertakes an explicit action research role in addition to the normal functional roles they hold in an organisation. Real-world work-based research is relevant and important to many full-time managers, consultants and members of organisations including those who choose to undertake higher degrees in business as part-time postgraduate students. Within these programmes a proposal for an insider action research project is often associated with important and interesting research projects that have already arisen in an organisation where the researcher works full-time, and are part of their existing role and established working relationships with key stakeholders. Ethical issues in organisationally located insider action research can differ from other forms of action research because of role duality, i.e. that the researcher holds an ongoing work role and power relationships associated with this as well as the action research role. Ethical issues can be associated with choices about alternative options, expected impacts and outcomes on the researcher, participants, organisation and stakeholders, and these are important considerations for academic supervisors, institutional review boards and human research ethics committees. 相似文献
34.
Miller JM Raymond J Fabian A Steeghs D Homan J Reynolds C van der Klis M Wijnands R 《Nature》2006,441(7096):953-955
Although disk accretion onto compact objects-white dwarfs, neutron stars and black holes-is central to much of high-energy astrophysics, the mechanisms that enable this process have remained observationally difficult to determine. Accretion disks must transfer angular momentum in order for matter to travel radially inward onto the compact object. Internal viscosity from magnetic processes and disk winds can both in principle transfer angular momentum, but hitherto we lacked evidence that either occurs. Here we report that an X-ray-absorbing wind discovered in an observation of the stellar-mass black hole binary GRO J1655 - 40 (ref. 6) must be powered by a magnetic process that can also drive accretion through the disk. Detailed spectral analysis and modelling of the wind shows that it can only be powered by pressure generated by magnetic viscosity internal to the disk or magnetocentrifugal forces. This result demonstrates that disk accretion onto black holes is a fundamentally magnetic process. 相似文献
35.
Andy PittEntec UK Ltd Northumbria House Manor Walks Cramlington Northumberland NE UP UK 《清华大学学报》2000,5(3)
IntroductionBeijing is the national capital of China,andthe capital of Beijing Municipality. The city islocated on the North China Plain,approximately1 50 km Northwest of the Bohai Sea at a north-latitude of40°.The municipality is approximately1 60 0 0 km2 in size,of which 2 / 3is mountainousarea encircling the western,northern and easternsides of the city. From the 1 990 census,the totalpopulation was 1 2 .9million,with 6. 4millionliving in urban areas,5.2 million living in the city,and … 相似文献
36.
Greenman C Stephens P Smith R Dalgliesh GL Hunter C Bignell G Davies H Teague J Butler A Stevens C Edkins S O'Meara S Vastrik I Schmidt EE Avis T Barthorpe S Bhamra G Buck G Choudhury B Clements J Cole J Dicks E Forbes S Gray K Halliday K Harrison R Hills K Hinton J Jenkinson A Jones D Menzies A Mironenko T Perry J Raine K Richardson D Shepherd R Small A Tofts C Varian J Webb T West S Widaa S Yates A Cahill DP Louis DN Goldstraw P Nicholson AG Brasseur F Looijenga L Weber BL Chiew YE DeFazio A 《Nature》2007,446(7132):153-158
Cancers arise owing to mutations in a subset of genes that confer growth advantage. The availability of the human genome sequence led us to propose that systematic resequencing of cancer genomes for mutations would lead to the discovery of many additional cancer genes. Here we report more than 1,000 somatic mutations found in 274 megabases (Mb) of DNA corresponding to the coding exons of 518 protein kinase genes in 210 diverse human cancers. There was substantial variation in the number and pattern of mutations in individual cancers reflecting different exposures, DNA repair defects and cellular origins. Most somatic mutations are likely to be 'passengers' that do not contribute to oncogenesis. However, there was evidence for 'driver' mutations contributing to the development of the cancers studied in approximately 120 genes. Systematic sequencing of cancer genomes therefore reveals the evolutionary diversity of cancers and implicates a larger repertoire of cancer genes than previously anticipated. 相似文献
37.
Bates A 《Population trends》2008,(133):28-34
A 'Postcode Best Fit' methodology has been developed by the Office for National Statistics to produce population estimates for a range of different geographies which are entirely consistent with each other, regardless of whether or not the estimates for one geography can be aggregated to produce estimates for another geography. This article describes the Postcode Best Fit methodology, its evaluation, limitations with some of the data sources used with the method, the application of the method for producing population estimates and case studies describing how the method has been used to produce bespoke population estimates to meet specific user requirements. 相似文献
38.
Locke DP Hillier LW Warren WC Worley KC Nazareth LV Muzny DM Yang SP Wang Z Chinwalla AT Minx P Mitreva M Cook L Delehaunty KD Fronick C Schmidt H Fulton LA Fulton RS Nelson JO Magrini V Pohl C Graves TA Markovic C Cree A Dinh HH Hume J Kovar CL Fowler GR Lunter G Meader S Heger A Ponting CP Marques-Bonet T Alkan C Chen L Cheng Z Kidd JM Eichler EE White S Searle S Vilella AJ Chen Y Flicek P Ma J Raney B Suh B Burhans R Herrero J Haussler D Faria R Fernando O Darré F Farré D Gazave E Oliva M 《Nature》2011,469(7331):529-533
'Orang-utan' is derived from a Malay term meaning 'man of the forest' and aptly describes the southeast Asian great apes native to Sumatra and Borneo. The orang-utan species, Pongo abelii (Sumatran) and Pongo pygmaeus (Bornean), are the most phylogenetically distant great apes from humans, thereby providing an informative perspective on hominid evolution. Here we present a Sumatran orang-utan draft genome assembly and short read sequence data from five Sumatran and five Bornean orang-utan genomes. Our analyses reveal that, compared to other primates, the orang-utan genome has many unique features. Structural evolution of the orang-utan genome has proceeded much more slowly than other great apes, evidenced by fewer rearrangements, less segmental duplication, a lower rate of gene family turnover and surprisingly quiescent Alu repeats, which have played a major role in restructuring other primate genomes. We also describe a primate polymorphic neocentromere, found in both Pongo species, emphasizing the gradual evolution of orang-utan genome structure. Orang-utans have extremely low energy usage for a eutherian mammal, far lower than their hominid relatives. Adding their genome to the repertoire of sequenced primates illuminates new signals of positive selection in several pathways including glycolipid metabolism. From the population perspective, both Pongo species are deeply diverse; however, Sumatran individuals possess greater diversity than their Bornean counterparts, and more species-specific variation. Our estimate of Bornean/Sumatran speciation time, 400,000?years ago, is more recent than most previous studies and underscores the complexity of the orang-utan speciation process. Despite a smaller modern census population size, the Sumatran effective population size (N(e)) expanded exponentially relative to the ancestral N(e) after the split, while Bornean N(e) declined over the same period. Overall, the resources and analyses presented here offer new opportunities in evolutionary genomics, insights into hominid biology, and an extensive database of variation for conservation efforts. 相似文献
39.
40.
High plant diversity is needed to maintain ecosystem services 总被引:3,自引:0,他引:3
Isbell F Calcagno V Hector A Connolly J Harpole WS Reich PB Scherer-Lorenzen M Schmid B Tilman D van Ruijven J Weigelt A Wilsey BJ Zavaleta ES Loreau M 《Nature》2011,477(7363):199-202
Biodiversity is rapidly declining worldwide, and there is consensus that this can decrease ecosystem functioning and services. It remains unclear, though, whether few or many of the species in an ecosystem are needed to sustain the provisioning of ecosystem services. It has been hypothesized that most species would promote ecosystem services if many times, places, functions and environmental changes were considered; however, no previous study has considered all of these factors together. Here we show that 84% of the 147 grassland plant species studied in 17 biodiversity experiments promoted ecosystem functioning at least once. Different species promoted ecosystem functioning during different years, at different places, for different functions and under different environmental change scenarios. Furthermore, the species needed to provide one function during multiple years were not the same as those needed to provide multiple functions within one year. Our results indicate that even more species will be needed to maintain ecosystem functioning and services than previously suggested by studies that have either (1) considered only the number of species needed to promote one function under one set of environmental conditions, or (2) separately considered the importance of biodiversity for providing ecosystem functioning across multiple years, places, functions or environmental change scenarios. Therefore, although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world. 相似文献